Liquid Ethane & Natural Gas Mixture

[Suprakash]

Hi,
I need to do a simulation on mixing of Liquid Ethane & Natural Gas & find out the commingled mixture property.
I modelled the same in DSWIM. The DWSIM file may be downloaded from below link. [http://www.filehosting.org/file/details/585380/Liquid%20Ethane%20&%20Natural%20Gas%20Mixture.dwxml]

Liquid Ethane:
Mass Flow rate 175 T/Hr. Accordingly I derived 3788405 Kg/d. Pressure 75 bar, Temp 25 C. Also I selected Phase molar fraction as “Overall Liquid”. Composition: C2 99.5%, C1 0.05%

Natural Gas:
Volumetric Flow rate 8 MMSCMD. Accordingly I derived 8000000 m3/d (standardised). Pressure 80 Bar, Temp 50 C. Composition: C1 94.4%, C2 3.9% rest higher hydrocarbons in proportion.

I am arriving at following result for the mixture–
Composition: C1 94%, C2 4.4% rest higher hydrocarbons in proportion.
Temp 47.47 C.
** I have used PR & SRK EOS.

My doubt is –

1. Have I made any mistake in modelling the scenario
2. Since pure Ethane is mixed, but still Ethane proportion in result mixture did not significantly increase. Did I miss something while defining the Ethane Mass Flow rate & Natural Gas Volumetric flow rate.
3. Also the pure ethane has critical pressure & temp close to 52 bar & 32 C, but when mixed with natural gas, the mixture phase envelope shows the Dew points completely in the negative side.

Pls help.

[Daniel Medeiros]

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